Stitch forming mechanism for sewing machines



-Feb; 28, 1933. C F RUBEL 1,899,828

STITCH FORMING MECHANISM FOR SEWING MACHINES Filed March 15, 1931 2 Sheets-Sheet l Feb. 28, 1933. c. F. RUBEL STITCH FORMING MECHANISM FOR SEWING MACHINES Filed March 15 1931 2 Sheets-Sheet Patented Feb. 28, 1933 UNITED STATES PATENT OFFICE;

CHARLES F. RUBEL-OF- CHICAGO, ILnrNoIs, ASSIGN'OR T UNIoN sPEcIAnMAcnINE COMPANY, on CHICAGO, ,rLLINoIs, A CORPORATION or IL INoIsv STITCH. FORMING MECHANISM non SEWING MAcHINEs Application filed March 15,1931. Serial No. 530,349.

The invention relates to new and useful improvements in a stitch forming mechanism for sewing machines, and more particularly to the spreader which engages the looper thread loop and positions the same for th entrance of the needles.

An object of the invention is to provide a spreader which is constructed so as. to positively engage the looper thread and carry the same laterally to one side of the looper for opening the looper thread loop for the needle to enter.

In the drawings, which show by way of illustration one embodiment of the inven tion: I

, Figure 3 is a view similar to Figure 2, butshowing the looper threads spread and posltioned for the needles to enter the same.

D Figure 4 is a view similar to Figure 3, but

showing the spreader as having released the looper thread loops and the needles as having entered the same. I

Figure 5 is a sectional View through the spreader on the line 55 of Figure 3.

Figure 6 is a view in section and showing more or .less diagrammatically one form of 5 seam made with the improved spreader.

The invention relates to a stitch forming mechanism wherein'a series of needles and cooperating loopers form stitches with the loops beneath the material extended so as 0 to engage the needle loops in adjacent rows of stitching. Cooperating with theloopers is a loop spreader which engages the looper thread of each looper and carries it laterally away from the looper in order to spread the 4 looper thread loop and extend the same so that it will be entered by two needles.

Referring more in detail to the drawings, the invention is shown as applied to a sewing machine which is provided with a work support 1 along which the material is fed by a feeding mechanism, including a feed dog 2. The material is held on the work support by a presser foot 3. The invention as illustrated is applied to a stitching mechanism which includes three needles, which are indi-' cat-ed at 4, 5 and 6 in the drawings. Cooperating with each needle beneath the work support is athread carrying looper, and these loopers are indicated at 7 8 and 9. The

loopers move in a direction parallel with the 1 line of feed for their-loop taking and loop shedding movements, and they move in'a direction substantially at right angles to the line of feed for their needle avoiding movement. Associated with the loopers is a spreader indicated at 10 in the drawings. This spreader is provided as shown with recesses in its under face forming two depend ing members having vertical walls 11. At

the bottom of each vertical wall is a laterally projecting finger 12.

The thread of the looper 7 is indicated at Z in the drawings. The thread of the looper 8 is indicated at Z in the drawings and the thread of the looper 9 is indicated at Z The threads of the three needles are indicated'respectively at n, n and n iln Figure 2 of the drawings theloopers are shown as having moved all the way in to the needle thread loops and the spreader has moved to the right as viewed in this figure, so'as to engage the looper threads running from the eyes of the loopers to the previous stitch. The depending 'members carrying the walls 11 and the fingers 12 are so disposed that when the loopers move laterally to the left as viewed in Figure 2, the spreader is moving to the right and will engage the looper threads. The looper thread Z only is engaged by the left-hand thread supporting finger 12, while both of the looper threads Z and Z are engaged by the supporting finger at the right. As the loopers begin their retracting movement and the spreader continues its lateral movement to the position. shown in Figure 3, the loop in the looper thread Z is positioned so. that both the needles 4 and 5 will enter this looper thread loop. The loops in the looper threads Z and Z will be brought together by the spreader and positioned so that both, of the needles 5 '3 and 6 will enter both of these needle thread.

loops. Thus it is that the looper threads, through the aid of the spreader, are positioned so that two needles enter each looper thread loop and therefore the looper thread loops in the finished seam extend about the needle thread loops in adjacent rows and the face of the fabric between the outer rows of needle loopswill be covered by the looperrthread loops. w

The stitch forming mechanism illustrated is particularly adapted for the uniting of two fabric sections with the edge portion of one overlapping the edge portion of the other. In Figure 6 of the drawings there is shown more orless diagrammatically two fabric sections-F and F. These fabric sections are lapped. When knitted fabrics are being stitched together it is preferable to trim the edge portions just prior to the placing of the same in lapped relation and the cut edge of the fabric section F is indicated at f, while the cut edge of the fabric section F is indicated at f. The needle 5 passes through the lapped section. The needle 4 passes through the fabric section F only and adjacent the edge portion f of the other fabric section. The needle 6 passes through the fabric section F only and close to the edge of the other fabric section. The loop in the looper thread Z, as shown in Figure 6, encircles both the needles i and 5. The loop in the looper thread Z encircles both of the needles 5 and 6, and the loop in the looper thread Z likewise encircles both of the needles 5 and 6. The edge f of the fabric section F is between the two needles 5' and 6, and therefore. this raw.

cut edge of the fabric will be very effectively covered by the loops in the looper threads Z and Z On the upper face of the fabric is a cross thread 0 which is looped about the needle thread loops.

The spreader described above is especially adapted for forming this particular stitch where the raw edge of the under-lapped section of fabric is covered by the loops in both the looper threads Z and P. This is brought about by positioning the holding fingers 12 and the retaining walls 11 so that the looper thread loops will be spread and positoned for the necdlesto enter in the manner described. The spreader is very positive in its handling of the looper threads, for the reason that the finger associated with the retaining wall holds the thread from slipping off the re taining wall, and therefore two threads may be held in engagement with one retaining wall as shown at the right in Figure 5. By giving to the spreader a different movement relative to the needles other positionings of the looper thread loops relative to the paths of, the needles may be accomplished with resulting different'concatenation of the loops. 'The essential feature of the invention resides in this forming of the spreader with a retaining finger which is associated with the retainer wall of the spreader, thus insuring that the looper threads will be supported from beneath and will not slip from the retainer walls andcause skipping of stitches, but will always be positively located in the-required position for the stitch formation intended. V

W hile a single supporting shank is provided for spreaders, it will be understood that the spreader may be-otherwise constructed. It is preferred, however, to form the spreader with the depending retaining walls and with the retaining fingers at the edges of the walls, as this is the best location in order to bring about an engagement with the looper threads at the time when they are drawn taut between the eyes of the looper and the previous stitch.

It will be obvious that minor changes in the details of construction and arrangement of parts may be made without departing from the spirit of the invention as set forth in the appended claims.

Having thus described the invention, what I claim as new and desire to secure byLetters Patent, is V 1. A spreader for spreading the looper thread in a stitch forming mechanism comprising a body portion having a recess in its under face forming a vertical retaining wall for the looperthread, said retaining wall having a projecting finger at the lower edge thereof adapted to retain the looper thread in contact with said retaining wall during the spreading of the looper thread loop.

2. A spreader for spreading the looper threads in a stitch forming mechanism comprising a body portion having recesses in the under face thereof forming spaced retaining walls adapted to engage certain of the looper thread loops for spreading the same, each retaining wall'having a horizontally extending finger at the lower edge thereof adapted to retain the looper threads on the retaining walls during the spreading of the i looper thread loops.

3. A spreader for spreading the looper thread loop in a stitch forming mechanism comprising a body portion having a recess in its under face forming a vertical retaining wall for the looper thread, said retaining wall having a projecting finger at the lower edge thereof extending outwardly from the wall a distance greater than the thickness of the looper thread so that a series of looper threads may be retained by said finger.

In testimony whereof, I affix my signature.

CHARLES F. RUBEL. 

